The special unit was originally supposed to be ready by 2019, but the plans are being accelerated amid a tide of aggressive rhetoric from its rival and neighbour North Korea, which has been threatening nuclear attacks on its enemies.

South Korea's defence minister Han Min-Koo said the special unit, known as the Korea Massive Punishment and Retaliation (KMPR) plan, would now be launched two years ahead of schedule.

"We are planning to set up a special brigade with the goal of removing or (at least) paralysing North Korea's wartime command structure," he told acting President Hwang Kyo-ahn, according to the Yonhap news agency.

He also warned of a "strategic or tactical provocation" from the North in the coming months.

The military unit forms part of a three-pronged defence strategy which includes an anti-missile system - the Korean Air and Missile Defence (KAMD) - which would trace and shoot down missiles heading for South Korea.

There is also a "Kill Chain" pre-emptive military strike programme to counter an imminent threat.

Kim used his televised New Year's message to boast his country was in the final stages of developing a long-range missile.